Foot-adjusting insert and method



Nov. 24, 1964 J. A. MlslAK 3,158,151

FooT-AnJusTING INSERT AND METHOD Filed May 13, 1960 United states Patent o ELISSI FTAD5USTING INSERT AND lvIiE'IIrI-GD Joseph A. Misiak, i554 W. Howard, Qhicago 26, lli. Filed Nlay I3, 1969, Ser'. No, 2S,925 3 Claims. (Cl. 12S- 2) called a bunion by the layman, but a true bunion involves deflection of the direction in which the great toe points beyond the joint, whereas an exostosis is an excrescence at the joint, generated by localized pressure, withoutmaterial deection of the great toe.

FIGURE 2 is a perspective view of a mold, or wax model, for a corrective insert for the condition of FIG- URE l;

FIGURE 3 is a plan View of the same model;

FIGURE 4 is a fragmentary section through such a device as that of FIGURE 2, in place in the shoe of the user, as on line 4 4 of FIGURE 3;

FIGURE 5 is a diagram indicating a hypothetical malformation of the skeletal structure involving a downward displacement of the third toe;

FIGURE 6 is a diagram of a condition known as harnmer toe, indicating the method of correcting that condition; and

FIGURE 7 is a partial view of equipment for preparing the permanent insert.

Actual completed inserts for the shoe, approximately according to FIGURES 2, 3, and 4 are ancient in the art, but in the past they have been originally formed of the materials that will permanently serve the purpose, either by measurement and guess work, or from a cast of the body member. Subsequent adjustments, if any, involved a great deal of difficulty and frequently the production of an entirely new device. Minor inaccuracies remained unnoticed until, after a long period of use, a new discomfort became troublesome. But the original fitting, and the fitting of a second appliance after the irst became unsuitable, were matters of approximation at best.

According to the invention, Iform a crude plaster mold, as by simply applying plaster, with bers imbedded in it to help it hold its shape, by manual application to form an impression of part or all of the part. In case of the abnormality of FIGURE l such a mold would have a contact area the same as that of the device illustrated in FIGURES 2 and 3, plus little extra along all its margms.

From the rough mold, I produce a wax model having the shape indicated in FIGURES 2, 3, and 4. The wax used for the purpose should be relatively soft and exible so that it has almost no resistance to bending and only a little resistance to plastic flow. In any event itvshould not have any greater resistance to displacement under applied pressure than the flesh of the part that will engage it when that iiesh is carrying the mechanical load to which it will later be subjected in regular use of the linished appliance.

In case of the particular appliance selected for illustration, after forming such an ephemeralwax model, the model is inserted in the shoe and the wearer walks around on its freely, and then the shoe and model are removed and inspected. This is what makes possible the precision Patented Non. 24, l @$4 adjustments according to the invention. Because the wax model has no resistance to bending and only slight resistance to plastic displacement, the model will yield to the flesh to a considerable extent, and if there are portions of the esh that normally tend to occupy positions spaced from the shoe to a greater extent than others, such low pressure spots will show up clearly on the wax model. More particularly, the direct pressure of the stocking against theupper surface of the model will embed the individual fibers of the stocking a little into the top surface as indicated by the irregular cross hatching at 10 in FIG- URE 3. The principal corrective structure, in this instance, is a horn 13, which cups the side of the foot just behind the exostosis 1l, and takes the mechancial pressure of the vamp. There will also almost invariably be several areas, such as those indicated in FIGURE 3 at l2, 14, and 16, Where the conformation of the foot under load has not lbeen perfectly compensated by the model and in these `areas rthe striations will be shallower, or entirely missing. Of course, it is possible to inspect the lower surface of the model also and occasionally get additional guidance, but if the supporting surface below the model is ilat, the upper surface adjustments stated develop a tinal shape that is transferable later from one shoe to any other of approximately the same general contour, without impairing the effectiveness of the insert.

The areas indicated in the soft wax model as ofv not quite sufticient thickness are now supplemented, as indicated in FIGURE 2, by placing tiny, soft gobs 18 of additional wax.. I have illustrated iive such globules placed in positions that correlate with low pressure areas indicated in FIGURE 3. The gobs are then ilattened out with a finger tip, and the original striations lll are erasedl by the finger tips or by the gentle momentary application of heat. As soon as the surface is smooth again the mold is again assembled and used a little, and a new pattern of striations Will result, often with some of the areas not quite suiciently compensated and some a little overcompensated, so that low pressure areas may appear at binds `and where it does not bind. Experience with the process explained here indicates that the nerve sensations of the patient are as notoriously inaccurate in this respect as in the case of an aching tooth, where a dentist finds that the patient frequently identies the wrong tooth.

FIGURES 2 and 3 represent, in the rst instance, the wax model, and later the subsequent finished insert, and the same applies to FIGURE 4. After the wax model has been fully compensated, which may require anything from two to a half dozen readjustrnents, depending on the extent of the abnormalities encountered, and the skill and judgment of the operator, the next step is to form a permanent insert of cured rubber o-f suitable yielding properties into the precise replica of the finished and adjustable Wax model. The pressure-bearing areas of the finished insert can thus be tailored by a skilled operator to be an exact replica o-f the natural contours of the loaded, active, foot or other body member, within a tolerance of the order of magnitude of ten or fifteen thousandths of an inch.

It will be obvious that the particular configuration selected for FIGURES l, 2, 3 and 4 is a matter of choice, and thatscores, if not hund-reds, of speciticallydiferent adjusting devices may be produced according to the process herein disclosed. These include prosthetic appliances for all parts of the body, such as the stumps of ampu tated limbs, hunchbacks, and large wens, etc. Any abnormal protrusion or concavity that occasions discomfort can thus be substantially modiiiedin the direction of normal configuration Referring now to FIGURE 5, I have indicated a hypothetical skeletal maltormation involving a downward displacement of the joint of the third toe. On the basis of X-rays that have identiiied this malformation with some precision, both in location and extent, I iirst form an adjusted wax model precisely as in` FIGURES l, 2, 3, and 4, except that the shape will be different. After arriving at a perfect compensation and uniform pressure distribution for the foot. I then change the adjustment model into a corrective model,l by elevating7 the upper surface of the adjustment model directly under the joint for the third toe Zit, as much as a sixteenth of an inch or so. From this intentionally'distorted wax model, I produce the permanent support, having the same corrective deviation. If the. correction imposed by the support is not too. great, the user finds it easy to get used to it and should use it for from three months to six months.

At the end of such a period of use, a new X-ray should l be taken to ascertain the extent to which the joint has moved up. In this way, by successive changes yto continue the slight corrective pressure on theI joint 20 over a period of from one to thi-ee years or so, the joint 2t) can be worked back up into pro-per alignment and the abnormality is permanently cured.

The malformation known as hammer toe is one lof the rather. common and troublesome conditions encountered, especially among Women who were provided with poorly fitted shoes during childhood or adolescence or both. This can be a very painful andunsightly condition.

As indicated in FIGURE 6, the wax model, and the finished corrective support, are shaped to include a top pad at 22 and a bottom pad at 24. rlFhe bottom pad is shaped to get a bearing at 26 against the tip of the toe and the top pad at 22 will get material downward pressure from the vamp of the shoe.

because the toe structure itself includes a plurality of bone articulations in it, it is possible in such an instance to form the lower pad 24 in such' a shape that there will be a small open space at 30, which will be present when the foot is not underload, but will tend to disappear whenever the user is standing or walking.

The pads may, on occasion, be anchored in the shoe, but in most instances better results are secured by providing thin side Walls 31 lying on either side of the toe and uniting the pads into a single tubular structure that will hold itself in place.

The exibility of the toe structure by reason of the skeletal articulations permits a substantially greater amount of adjustment each time, so far as actual geometrical displacement is concerned, but the actual rnechanical loads generated are probably much smaller than in the correction according to FIGURE 5. Adjustments according to FIGURE 6 are a little more ticklish than according to FIGURE 5, but none of these corrections, nor, for that matter, the mere adjustment compensation of FIGURES l to 4 inclusive, can be achieved in a satisfactory way without some practice and considerable care and manual skill. It is impossible to put into Words all the details of such sensory and manual skills, but the foregoing explanation is believed to be adequate to enable any person with good muscular coordination and normal sense of touch to acquire enough skill to produce satisfactory results in all but the mostfditicult cases. It is well known that such skills continue to increase for many years, if they are exercised with a fair degree of continuity.

In military service the unavoidable discomforts and hardships to which personnel must subject themselves are saisi extreme, and anything that will mitigate such hardships assumes additional importance. Footwear capable of enduring military service must be unusually strong and heavy. The continued use of any shoe by the same individual soon changes the initially flat upper surface of the heavy sole to'secure a rough approximation -to the loaded contour of the member bearing on it. Until this has occurred the shoe is uncomfortable and not yet broken in. After it has occurred, the shoe is broken in only for one wearer, and another person who wears the same size shoe will have to .break the shoe in over again. This second breaking is often more extensive and diiiicult than the rst, to such an extent that present practice with military personnel is to discard vsuch footwear rather than attempt to make it serve another user.

According to the invention, the heavy army shoe is designed with about 3732" of extra ventical inside dimension, and an adapter according to FIGURE 3 is made at the .timeA the shoe is purchased, for every purchaser, and extended to underlie the entirek foot and abut the vamp around the edges.` Thus the shoe is notonly comfortable hnmediately, without any breaking in, but the sole proper remains, of substantially unaltered fiatness. Among military personnelthus equipped, men withk feet of approxil fession calls- .a Unnas paste boot.

mately the same overall size vcan take care of emergencies by exchange or loan of shoes and .the athletic effectiveness of personnel is substantially unimpaired except during the few moments necessary to put thev shoes on. The shoes remain easily exchangeable and replaceable because the shoe propernever is broken in. Each user has his own personally fitted adjustment for a shoe with an entirely fiat sole. I

Ulcers are often protected with what the medical proa This is an enclosure of gelatin reinforced with layers of cheese cloth or the like. It is much more expensive than latex according to the invention and hardens much too hard during use. The same application technique builds up a reinforcing boot for a sprained ankle and is so cheap that after it has .been worn a few days and the swelling has gone down a new boot can be substituted. The same technique will be etleo tive in the formulation of light weight corsets for sprained backs. Ordinary casts for such uses commonly weigh about l5 pounds, but a good latex cast according to the invention need weigh only about J5 pounds.

It is common to insert self hardening plastic inserts under the edge of an ingrown toenail to guide the parts in growing back into normal relationship. Those inserts get much too hard for comfort. The same insert made from latex, according to the invention, can also be loadedv with enough iiller so that it will shrink a little during use and this shrinkage assists in'helping the parts grow back into normal relationship.

Referring now to FIGURE 7, I have indicated a steel lower holder, or flask, 32 and an approximate replica or cope, 34`placed above the tiask 32. The asks and cope denne a cavity of size ample to include the proposed im sert 38, with a generous clearance around it in all directions. The inner lcavity is substantially completely einv closed, except that it is advantageous to provide'one of the parts 32 and 34 with tiny grooves 36 which leave small peripheral outlets from which excess material vcan exudeV as the molds` are pressed together.

With an insert of the shape of FIGURES 2, 3, and 4 I prefer :to embed the wax model 38, first in a mass of plaster of Paris, indicated at 4t), with a iiat peripheral surface at 42 around the insert, and allow that much material to setand harden enough to hold its shape. Subsequently I turn the parts illustrated upside down and till the space above the insert with identical plaster of Paris, so thatthe space at 44 above the insert and above the rst plaster of Paris ll ast 4t), is also filled. After this is allowed to harden, it is not difficult to separate the two halves of the complete mold thus formed. A little grease or thin glassine paper on top of the till 40 may be desirable to maintain a separation between the upper fill 44 and the lower lill 40.

The next step is to prepare a special mix of latex that can subsequently harden by the application of gentle heat into a substantially solid mass without irregularities anywhere. For 'the shapes shown the parts would be placed the other side up and a pile of this fairly viscous material would be poured on top of the iill 44 so that fthe grooves at 46 and 47 would be completely filled by gravity. Then the other mold at 40 will be pressed down onto -the mass and a slight excess of rubber material should be provided, which can exude through the weep holes 36 as the parts are pressed into firm contact with each other. After the assembly is complete it becomes immaterial which side up the parts are placed.

The next step is to position the assembled parts with the lower one resting on ,a hot surface and a hot flat iron or the equivalent resting on top of the other one. But the thermal conductivity of the metal shell is so great that satisfactory results may be obtained by delivering heat to one side only. Because plaster of Paris is a relatively poor heat conductor it `takes quite a little time for the heat to work through the plaster of Panis and raise the temperature of the latex to a point where it polymerizes into the finished article. A little experience and judgment is required yin this respect, but the tolerance of the material appears to be such that a wide margin of error makes no material diierence in the product. if the first filling is kept hot for 30 minutes and cornes out a little soft `and fluid in the center, a second filling can be similarly heated for 60 or 90 minutes and will not be too hard. When it is contemplated that the patient will require attention at intervals for .some time Ito come, it is desirable to produce two iinished rubber casts before the plaster of Paris mold is thrown away. In that way one of the rubber casts can be used by the patient and the other one filed away as a more convenient and permanent record for future use than the soft wax model would be.

Partially polymerized substantially liquid latex preparations are available on the market in a wide variety of qualities, and generally all of them can be effectively used for the process disclosed, but not in the form in which they are sold. They are sold in a form suitable for coating the outside of an article by dipping it into the mass of latex, or by spraying or painting the latex onto the article. This easily produces a latex covered article or, if the latex envelope is the desired product, it can be slit and peeled olf the mold and constitute the final product.

With such latex preparations it is impossible to produce solid articles of material thickness such as are required for the practice of this invention. The initial warming of the material in the molds forms a continuous, solid, impervious skin extending from l percent to 30 percent i1 toward the center of the mass, leaving a liquid interior. Further heating might volatilize the water inside and generate pressure, or, if the water succeeded in escaping, leave spaces in the center. In any event the finished product would be entirely unsatisfactory.

I have found that by the admixture of approximately the right amount of solid powders that tend to hydrate and absorb water, molecule by molecule, with or without cooperating material that serves as a mere iiiler, it is practical to prepare a mix that will have increased viscosity before heating and thus be more easily handled in getting it into the mold, and that will cure adequately all the way through into a solid mass that has a greater yielding action than common vulcanized rubber, such as might form the tread of an automobile tire.

To the best of my knowledge and belief those professing skill in the uses of aqueous latex emulsions of all sorts, are unanimously of the opinion that they cannot be used at all for the immediate production of compact solid shapes, such as a block one-half inch thick, or such a prosthetic device as that illustrated in the drawings.

Cit

In attempting to do so, I have repeatedly filled suchv a mold as. is illustrated in' FIG. 7, with the most con"-v centrated emulsion available to me, which is identified n the trade as Goodrich 61-1000, and which contains only about 25% of water. When such an assembly is heated to complete the curing, or polymerization of the latex, a water-tight external skin forms first, and after the boiling temperature is exceeded, the accumulated steam pressure inside finds an explosive release that ruins the product and sometimes other things.

However, mixing with the latex, before it is put in the mold, only a minor trace of plaster of Paris, the same identical procedure in every respect, results in the unimpeded gradual liberation of steam until such evolution ceases gradually. In a typical test, producing a simple rectangular parallelepipedon l x 11/2 X 716", about 2,000 Wattslwas used to heat metal heating elements in contact with the metal of the flask 32 and cope 34, for 45 minutes. Rather vigorous evolution of steam began in about 15 minutes and died away at the end of 35 minutes. After 10 minutes more, the heat supply was cut oif and the assembly allowed to cool in air for half an hour. Subsequent inspection and test of the block showed it to be good sound rubber well suited for such articles as are illustrated in the drawings.

The particular test mentioned employed 30 grams of 61-1000 emulsion, and 1 gram of plaster of Paris. Based on scores of similar operations, chiefly inthe preparation'of prosthetic devices according to the present inven-` tion, I Iind that a mere trace of plaster of Paris, or magnesium chloride, or any other foreign water soluble ioniza# ble material will cause the emulsion to perform as abovev set forth. Whether this is because the foreign substance provokes a preliminary assembly of the dispersed latex particles into coniigurations such that preliminary polymerization proceeds throughout the entire mass and no steam is trapped, I am unable to state.

I am able to state that with only a trace of the presumed catalyst, the heating must be slow and prolonged to avoid disaster. With enough plaster of Paris to take up water of crystallization amounting to one-third of the water present, it requires skill to get the material into the mold before it sets prematurely. As the amount is decreased, the setting period increases. Also, as the plaster of Paris is increased, .the hardness increases somewhat so that a considerable variation in stiffness can be obtained at will, down to a close approximation to the softness of pure rubber when the minimum effective additive is employed.

When the mold is according to FIG. 7, the plaster of Paris of the mold itself can be dried by preheating and ythen cooling. In that condition the mold itself acts to withdraw a great deal of water from the mass being cured.

Others may readily adapt the invention for use under various conditions of service by employing one or more of the novel features involved or equivalents thereof. The materials I have used to promote the complete curing of the latex mass include magnesium oxide, bentonite, magnesium chloride, zinc oxide, powdered alum, calcium carbonate. methyl cellulose, and Portland cement. When the completed mix is heated, the finished product may be obtained in an hour or so. But the mix will eventually cure at room temperature, if allowed to stand for a day or two.

I claim:

l. The method of preparing an adjusting insert, for footwear and analogous uses, which comprises: approximating the desired shape in a model of yielding material f patients foot in the shoe and thereby generating surface 'y impressions in the model in the nature of striations corresponding to those of the skin or garment transmitting the working load to the model; readjusting the thickness of the model locally over small areas,; vvyhich.. small areas jointly include the entire loade bearing supericies ofx said,

model, to change the pressure distribution into a. new` and more regular patternby lowering areas Where the impressions are deep and lilling. up` areasy Where the impressions are light or completely missing andthereby smoothirng out the rst setof service impressions; subjecting the readjusted model to a second applica-tion of. service loading and stresses; repeating the cycle. o service loading, readjustrnent, smoothing out and loading, until a inal shape is arrived at in which the service loading follows a relatively uniform and physiologically helpful pattern, in harmony with the anatomical idiosyncrasies of the user; and from the nally adjustedy modelpreparing a permanent insert of durable materialV and of identical shape, adapted to carry service loads and retain its shape unaltered.

2. The method of claim l, and additionally purposefully altering a minor portion of the shape of the model in a desired direction to correct an observed anatomical malformation of a patients foot and to a degree small enough to be tolerated by the patient; preparing a permanent insert from said altered model; subjecting said permanent insert to regular use for a period of at least several months; then preparing a second model according to claiml having a slightly different shape due to use of the irst permanent insert; purposefully altering the shape of said. second model in the direction of further correction; and preparing a second permanent insert for a second period of regular use.

3. A tailored foot-supporting insertl for shoes com-- prising a non-toxic solid mass; havingv substantial constancyA ot vo1ume,'but resilient as, to shape, Asaid mass being of variable thickness throughout said load 'bearin,g,

of depressions corresponding to the'anatornical idio-y syncrasies ot the wearer,` andthe. shoe itseli remains interchangeable with other shoes previously Worn by other users in conjunction with other inserts according tothe invention. u

Reereuces Cited inthe tile of this patent` UNITED STATES PATENTS 

1. THE METHOD OF PREPARING AN ADJUSTING INSERT, FOR FOOTWEAR AND ANALOGOUS USES, WHICH COMPRISES: APPROXIMATING THE DESIRED SHAPE IN A MODEL OF YIELDING MATERIAL HAVING NEGLIGIBLE RESTITUTION WHEN STRESS IS REMOVED; POSITIONING THE APPROXIMATE MODEL IN A PATIENT''S SHOE AND SUBJECTING IT TO SERVICE LOADING AND STRESSES WITH THE PATIENT''S FOOT IN THE SHOE AND THEREBY GENERATING SURFACE IMPRESSIONS IN THE MODEL IN THE NATURE OF STRIATIONS CORRESPONDING TO THOSE OF THE SKIN OR GARMENT TRANSMITTING THE WORKING LOAD TO THE MODEL; READJUSTING THE THICKNESS OF THE MODEL LOCALLY OVER SMALL AREAS, WHICH SMALL AREAS JOINTLY INCLUDE THE ENTIRE LOAD BEARING SUPERFICIES OF SAID MODEL, TO CHANGE THE PRESSURE DISTRIBUTION INTO A NEW AND MORE REGULAR PATTERN BY LOWERING AREAS WHERE THE IMPRESSIONS ARE DEEP AND FILLING UP AREAS WHERE THE IMPRESSIONS ARE LIGHT OR COMPLETELY MISSING AND THEREBY SMOOTHING OUT THE FIRST SET OF SERVICE IMPRESSIONS; SUBJECTING THE READJUSTED MODEL TO A SECOND APPLICATION OF SERVICE LOADING AND STRESSES; REPEATING THE CYCLE OF SERVICE LOADING, READJUSTMENT, SMOOTHING OUT AND LOADING, UNTIL A FINAL SHAPE IS ARRIVED AT IN WHICH THE SERVICE LOADING FOLLOWS A RELATIVELY UNIFORM AND PHYSIOLOGICALLY HELPFUL PATTERN, IN HARMONY WITH THE ANATOMICAL IDIOSYNCRASIES OF THE USER; AND FROM THE FINALLY ADJUSTED MODEL PREPARING A PERMANENT INSERT OF DURABLE MATERIAL AND OF IDENTICAL SHAPE, ADAPTED TO CARRY SERVICE LOADS AND RETAIN ITS SHAPE UNALTERED. 